Low temperature high reliability alloy for solder hierarchy

Patent metadata

Field	Value
Publication number	US-10322471-B2
Application number	US-201515326180-A
Country	US
Kind code	B2
Filing date	Jul 15, 2015
Priority date	Jul 21, 2014
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

A lead-free, antimony-free solder alloy_suitable for use in electronic soldering applications. The solder alloy comprises (a) from 1 to 4 wt. % silver; (b) from 0.5 to 6 wt. % bismuth; (c) from 3.55 to 15 wt. % indium, (d) 3 wt. % or less of copper; (e) one or more optional elements and the balance tin, together with any unavoidable impurities.

First claim

The invention claimed is:

1. A lead-free, antimony-free solder alloy consisting of:
(a) from 1 to 4 wt. % silver
(b) from 0.5 to 6 wt. % bismuth
(c) from 7 to 12 wt % indium
(d) from 0.01 to 3 wt % copper
(e) from 0.005 to 1 wt. % of titanium
(f) one or more of the following elements
0 to 1 wt. % nickel
0 to 1 wt. % manganese
0 to 1 wt. % of rare earths, such as cerium
0 to 1 wt. % of chromium
0 to 1 wt. % germanium
0 to 1 wt. % of gallium
0 to 1 wt. % of cobalt
0 to 1 wt. % of iron
0 to 1 wt. % of aluminum
0 to 1 wt. % of phosphorus
0 to 1 wt. % of gold
0 to 1 wt. % of tellurium
0 to 1 wt. % of selenium
0 to 1 wt. % of calcium
0 to 1 wt. % of vanadium
0 to 1 wt. % of molybdenum
0 to 1 wt. % of platinum
0 to 1 wt. % of magnesium

(g) the balance tin, together with any unavoidable impurities.

2. The solder alloy according to claim 1 , wherein the alloy comprises from 1.2 to 3.8 wt. % silver.

3. The solder alloy according to claim 1 , wherein the alloy comprises from 2 to 4 wt. % silver, from 1 to 6 wt. % bismuth and from 7 to 10 wt. % indium.

4. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 7 to 9 wt. % indium and from 0.1 to 1.5 wt. % copper.

5. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt, % indium, from 0.3 to 0.8 wt. % copper and from 0.01 to 0.05 wt. % titanium.

6. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt. % indium, from 0.3 to 0.8 wt. % copper, from 0.005 to 0.05 wt. % titanium and from 0.005 to 1 wt. % germanium.

7. The solder alloy according to claim 1 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 7 to 9 wt. % indium, from 0.3 to 0.7 wt. % copper, and from 0.001 to 0.03 wt. % germanium.

8. The solder alloy as claimed in claim 1 , wherein the alloy has a liquidus temperature of 215° C. or less.

9. A method of forming a solder joint comprising:
(i) providing two or more work pieces to be joined;
(ii) providing a solder alloy consisting of:
(a) from 1 to 4 wt. % silver
(b) from 0.5 to 6 wt. % bismuth
(c) from 7 to 12 wt. % indium
(d) from 0.01 to 3 wt. % or less of copper
(e) from 0.005 to 1 wt. % of titanium
(f) one or more of the following elements:
0 to 1 wt. % nickel
0 to 1 wt. % of titanium
0 to 1 wt. % manganese
0 to 1 wt. % of rare earths, such as cerium
0 to 1 wt. % of chromium
0 to 1 wt. % germanium
0 to 1 wt. % of gallium
0 to 1 wt. % of cobalt
0 to 1 wt. % of iron
0 to 1 wt. % of aluminum
0 to 1 wt. % of phosphorus
0 to 1 wt. % of gold
0 to 1 wt. % of tellurium
0 to 1 wt. % of selenium
0 to 1 wt. % of calcium
0 to 1 wt. % of vanadium
0 to 1 wt. % of molybdenum
0 to 1 wt. % of platinum
0 to 1 wt. % of magnesium

(g) the balance tin, together with any unavoidable impurities; and

(iii) heating the solder alloy in the vicinity of the work pieces to be joined.

10. A lead-free, antimony-free solder alloy consisting of:
(a) from 1 to 4 wt. % silver;
(b) from 0.5 to 6 wt. % bismuth;
(c) from 4.5 to 10 wt. % indium;
(d) from 0.01 to 3 wt. % copper;
(e) from 0.05 to 0.25 wt. % of nickel;
(f) from 0.01 to 0.05 wt. % manganese;
(g) optionally, from 0.005 to 1.0 wt. % phosphorus;

and the balance tin, together with any unavoidable impurities.

11. The solder alloy according to claim 10 , wherein the alloy comprises from 2 to 4 wt. % silver, from 2 to 4.5 wt. % bismuth, from 4.5 to 10 wt. % indium, from 0.1 to 1.5 wt. % of copper and from 0.05 to 0.25 wt. % of nickel.

12. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 5 to 8 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % of nickel.

13. The solder alloy according to claim 12 , wherein the alloy comprises from 2.5-3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

14. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % of silver, from 2.5 to 4 wt. % bismuth, from 5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % of nickel.

15. The solder alloy according to claim 14 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

16. The solder alloy according to claim 15 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, 6 wt. % indium, from 0.1 to 1.5 wt. % copper and from 0.05 to 0.25 wt. % nickel.

17. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 4 wt. % silver, from 2.5 to 4 wt. % bismuth, from 5 to 6.5 wt. % indium, from 0.1 to 1.5 wt. % copper, from 0.05 to 0.25 wt. % nickel and from 0.01 to 0.05 wt. % manganese.

18. The solder alloy according to claim 17 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. indium, from 0.3 to 0.7 wt. % copper, from 0.05 to 0.25 wt. % nickel and from 0.005 to 0.05 wt. % manganese.

19. The solder alloy according to claim 10 , wherein the alloy comprises from 2.5 to 3.5 wt. % silver, from 2.5 to 3.5 wt. % bismuth, from 5.5 to 6.5 wt. % indium, from 0.3 to 0.8 wt. % copper, from 0.05 to 0.4 wt. % nickel, from 0.01 to 0.05 wt. % manganese and from 0.01 to 0.15 wt % phosphorous.

20. The solder alloy according to claim 10 comprising:
(a) 4.5 to 8 wt. % of indium; and
(b) from 0.005 to 1 wt. % phosphorus.

21. The solder alloy of claim 20 comprising from 2 to 4 wt. % silver, from 2 to 4 wt. % bismuth, from 0.1 to 0.8 wt. % copper and from 0.01 to 1 wt. % phosphorus.

Assignees

• Alpha Assembly Solutions Inc

Inventors

• Choudhury Pritha
• De Avila Ribas Morgana
• Mukherjee Sutapa
• Sarkar Siuli
• Pandher Ranjit
• Bhatkal Ravindra
• Singh Bawa

Classifications

• H10W72/07336

  Soldering or alloying · CPC title

• H10W72/352

  comprising metals or metalloids, e.g. solders · CPC title

• B23K35/0227

  Rods or wires (B23K35/0244 takes precedence) · CPC title

• H01L2224/29157

  Electricity · mapped topic

• B23K2101/42

  Printed circuits · CPC title